The Academy's Evolution Site
Biological evolution is one of the most fundamental concepts in biology. The Academies are involved in helping those interested in the sciences understand evolution theory and how it is incorporated across all areas of scientific research.
This site provides a wide range of tools for students, teachers, and general readers on evolution. It contains key video clips from NOVA and WGBH's science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol that symbolizes the interconnectedness of all life. It is used in many religions and cultures as an emblem of unity and love. It has many practical applications as well, such as providing a framework to understand the history of species, and how they react to changing environmental conditions.
The first attempts at depicting the world of biology focused on separating species into distinct categories that had been distinguished by their physical and metabolic characteristics1. These methods rely on the collection of various parts of organisms or short fragments of DNA have greatly increased the diversity of a tree of Life2. These trees are mostly populated by eukaryotes, and bacterial diversity is vastly underrepresented3,4.
Genetic techniques have significantly expanded our ability to depict the Tree of Life by circumventing the requirement for direct observation and experimentation. Particularly, molecular methods enable us to create trees by using sequenced markers like the small subunit ribosomal gene.
에볼루션코리아 of Life has been significantly expanded by genome sequencing. However, there is still much biodiversity to be discovered. This is particularly relevant to microorganisms that are difficult to cultivate and are typically present in a single sample5. A recent analysis of all genomes has produced a rough draft of the Tree of Life. This includes a wide range of archaea, bacteria and other organisms that have not yet been isolated, or their diversity is not well understood6.
The expanded Tree of Life is particularly useful in assessing the diversity of an area, assisting to determine whether specific habitats require special protection. This information can be used in a range of ways, from identifying the most effective treatments to fight disease to enhancing the quality of the quality of crops. This information is also extremely valuable for conservation efforts. It helps biologists determine those areas that are most likely contain cryptic species with potentially significant metabolic functions that could be at risk from anthropogenic change. While conservation funds are important, the best way to conserve the world's biodiversity is to equip more people in developing countries with the information they require to act locally and support conservation.
Phylogeny
A phylogeny, also known as an evolutionary tree, illustrates the relationships between various groups of organisms. By using molecular information, morphological similarities and differences or ontogeny (the course of development of an organism) scientists can construct an phylogenetic tree that demonstrates the evolutionary relationship between taxonomic groups. Phylogeny is essential in understanding biodiversity, evolution and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 Determines the relationship between organisms with similar characteristics and have evolved from an ancestor with common traits. These shared traits can be either homologous or analogous. Homologous traits are identical in their evolutionary origins while analogous traits appear similar but do not have the same origins. Scientists put similar traits into a grouping referred to as a Clade. For instance, all the organisms in a clade share the trait of having amniotic eggs and evolved from a common ancestor which had these eggs. A phylogenetic tree is then constructed by connecting clades to determine the organisms who are the closest to each other.
To create a more thorough and precise phylogenetic tree scientists use molecular data from DNA or RNA to identify the connections between organisms. This information is more precise than morphological information and gives evidence of the evolutionary history of an organism or group. Molecular data allows researchers to determine the number of organisms who share the same ancestor and estimate their evolutionary age.
The phylogenetic relationship can be affected by a number of factors that include phenotypicplasticity. This is a type behaviour that can change due to particular environmental conditions. This can cause a trait to appear more similar to a species than another which can obscure the phylogenetic signal. This problem can be mitigated by using cladistics, which is a a combination of homologous and analogous features in the tree.
Additionally, phylogenetics can help predict the length and speed of speciation. This information can help conservation biologists decide which species to protect from extinction. It is ultimately the preservation of phylogenetic diversity that will result in an ecologically balanced and complete ecosystem.
Evolutionary Theory
The central theme of evolution is that organisms develop various characteristics over time due to their interactions with their environments. Many theories of evolution have been developed by a variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing gradually according to its requirements, the Swedish botanist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits can cause changes that could be passed on to offspring.
In the 1930s and 1940s, ideas from a variety of fields--including natural selection, genetics, and particulate inheritance--came together to form the current synthesis of evolutionary theory which explains how evolution occurs through the variations of genes within a population and how those variations change over time due to natural selection. This model, which incorporates genetic drift, mutations, gene flow and sexual selection is mathematically described.
Recent advances in evolutionary developmental biology have shown the ways in which variation can be introduced to a species through mutations, genetic drift or reshuffling of genes in sexual reproduction, and even migration between populations. These processes, along with others such as directional selection or genetic erosion (changes in the frequency of a genotype over time), can lead to evolution, which is defined by change in the genome of the species over time and the change in phenotype over time (the expression of that genotype within the individual).
Incorporating evolutionary thinking into all areas of biology education can improve students' understanding of phylogeny as well as evolution. In a study by Grunspan and co. It was found that teaching students about the evidence for evolution boosted their acceptance of evolution during an undergraduate biology course. For 에볼루션 카지노 사이트 about how to teach evolution, see The Evolutionary Power of Biology in All Areas of Biology or Thinking Evolutionarily A Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Traditionally, scientists have studied evolution through looking back, studying fossils, comparing species and studying living organisms. But evolution isn't a thing that happened in the past, it's an ongoing process happening right now. Viruses reinvent themselves to avoid new drugs and bacteria evolve to resist antibiotics. Animals alter their behavior as a result of a changing world. The results are often visible.
But it wasn't until the late 1980s that biologists understood that natural selection could be observed in action as well. The key is that different traits confer different rates of survival and reproduction (differential fitness) and can be transferred from one generation to the next.
In the past, when one particular allele - the genetic sequence that defines color in a group of interbreeding organisms, it could rapidly become more common than the other alleles. Over time, this would mean that the number of moths with black pigmentation could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
Observing evolutionary change in action is easier when a particular species has a fast generation turnover like bacteria. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that are descended from a single strain. Samples of each population have been collected frequently and more than 500.000 generations of E.coli have passed.
Lenski's research has revealed that mutations can alter the rate of change and the rate of a population's reproduction. It also proves that evolution is slow-moving, a fact that some people find hard to accept.
Microevolution can be observed in the fact that mosquito genes that confer resistance to pesticides are more prevalent in populations where insecticides have been used. Pesticides create an exclusive pressure that favors individuals who have resistant genotypes.
The rapid pace at which evolution takes place has led to an increasing awareness of its significance in a world that is shaped by human activity, including climate change, pollution, and the loss of habitats that prevent many species from adapting. Understanding the evolution process can aid you in making better decisions about the future of our planet and its inhabitants.